Oxfordshire Woodland Group

How do I measure the standing volume of this big beech tree ?

I would imagine that the trunk could be measured using a "frustrum of cone" equation requiring a measurement of the diameter (circumference) at both the bottom and top of the trunk. The bottom is easy to measure but the top of the trunk is probably about 70 ft up and hence I am unable to take that measurement. I would also need to be able to measure or estimate the tree trunk height and would appreciate some help on how this should be done.

What branchwood volume expressed as say a percentage of trunk volume might be contained in the crown of the tree ?

Chilterns